Plasma compression apparatus

ABSTRACT

Apparatus to compress a plasma or ionized medium by the use of a generally spherical field produced by a generally spherical winding or field means. The current flows generally in the same direction on the conductors which surround an envelope containing the plasma to produce a weak field or null field in the central region of the envelope with a stronger field surrounding this weak field which effectively compresses the plasma into the central region.

United States Patent [72] Inventor Robert E. Uleski 1410 West 21st st., Lorain, Ohio 44042 [21] Appl.No. 791,018

[22] Filed Jan. 14, 1969 [45] Patented Oct. 19,1971

[54] PLASMA COMPRESSION APPARATUS 9 Claims, 4 Drawing Figs.

[52] U.S.Cl 315/111, 176/1,176/3, 313/154, 313/231 [51] Int. Cl .,H0lj 17/14, HOSh 1/10 [50] Field of Search 313/154, 161,231; 176/1, 3,7; 315/236, 344,111

[56] References Cited UNITED STATES PATENTS 2,953,718 9/1960 Ducati 176/1 X 3,002,912 10/1961 Spitzer, Jr 313/161 X 3,031,398 4/1962 Tuck 176/7 X 3,445,722 5/1969 Scott et a1 313/231 X Primary ExaminerRoy Lake Assistant Examiner-Palmer C. Demeo Attorney-Woodling, Krost, Granger and Rust ABSTRACT: Apparatus to compress a plasma or ionized medium by the use ofa generally spherical field produced by a generally spherical winding or field means. The current flows generally in the same direction on the conductors which surround an envelope containing the plasma to produce a weak field or null field in the central region of the envelope with a stronger field surrounding this weak field which effectively compresses the plasma into the central region.

HIGH POTENTIAL SOURCE VACUUM SOURCE 5 HIGH POTENTIAL sounce- VACUUM SOURCE SOURCE INVENTOR.

' ROBERT c. ULESKI F HG. I

BACKGROUND OF THE INVENTION The prior art has disclosed many different arrangements for compressing plasma and many are described in Scientific American for July 1968, entitled: The Leakage Problem in Fusion Reactors." One of the more simple arrangements for compressing plasma was a generally solenoid or cylindrical shape winding which had a substantially uniform field along the axis of the solenoid. Applying sufficient power to the solenoid winding could achieve highly concentrated magnetic fields along the axis of the winding. However, when such field exceeds one kilogauss, a phenomenon called anomolous diffusion takes place and the plasma in an envelope within the solenoid tends to diffuse from this concentrated field and escape to weaker field areas. Accordingly, the plasma leaked out the two ends of the solenoid coil. This solenoid apparatus developed flute" instability, wherein random particle motion of the ions causes a typeof helical flutes to be formed on the surface of the plasma and eventually the flutes become so large that streams of the plasma touched the walls of the envelope which dissipated thermoenergy, thereby preventing the desired compression of plasma In an attempt to compress the plasma, the solenoid type winding was changed by some experimenters to include two large coils near the end of the solenoid. This did give a pinch effect in the plane of each coil and the plasma was contained longitudinally between the two coils. However, when it is compressed still further, the plasma did escape out the two ends of the envelope winding. This apparatus still had flute instability, again preventing a high degree of compression of the plasma.

Another form of apparatus was a torus or doughnut shape with the plasma contained within the hollow doughnut. The plasma with increased magnetic fields above one kilogauss still diffused outwardly to touch the walls of the envelope to lose thermoenergy and additionally this apparatus had flute instability. On this torus, an additional helical winding was placed in an attempt to eliminate the flute diffusion in order to set up a magnetic field perpendicular to these flutes. However, another form of diffusion called Bohn difiusion took place, again preventing compression of the plasma beyond a certain amount.

Cusp fields have been tried as established by two windings parallel to each other by the conducting current in opposite directions but this cusp field was also defective in attempting to compress the plasma. The cusp field apparatus failed to achieve the required plasma compression because the plasma tended to leak out along the magnetic field lines. This is described in Plasma Physics by Cambel & Cambel, published by D. C. Heathe & Company, 1965.

Another apparatus was the Stellarator which was a single winding disposed in a FIG. 8. This FIG. 8 was a hollow tube containing the plasma and was designed to prevent the ions from drifting to the outer edge of the envelope by a proper dimensioning of the FIG. 8, so that the ions would make one loop and be near the outer edge which would then become the other half of the FIG. 8 and be near the inner surface of the envelope. This apparatus still had general instabilities and manifested a Bohm type of difiusion as a form of instability.

A more recent form of cusp field was a multipole apparatus which, for example, had four generally parallel current-carrying rods carrying current in the same direction with return current through the outer wall and the plasma was injected into the central region of the four rods. Again this produced a cusped field with the energetic particles again tending to escape along the magnetic field lines.

Accordingly, an object of the invention is to produce a device to obviate the above-mentioned disadvantages.

Another object of the invention is to provide apparatus to produce a generally spherical field.

Another object of the invention is to provide an apparatus establishing a weaker field surrounded by a stronger field to contain and compress plasma in the area of the weaker field.

Another object of the invention is to provide apparatus producing a spherical field with substantially three-dimensional symmetry and with a weak or null field generally in the central region.

Another object of the invention is to provide apparatus for compressing plasma in substantially all directions to prevent escape or leakage of the plasma.

SUMMARY OF THE INVENTION The invention may be incorporated in plasma compression means for compressing a plasma toward a centrally disposed three-dimensional region, said plasma compression means comprising, in combination, means for generating a plasma, three-dimensional envelope means surrounding said threedimensional region for containing said plasma substantially all around said three-dimensional region, and three-dimensional magnetic field means having a three-dimensional magnetic field substantially surrounding said three-dimensional envelope, and said three-dimensional field having a three-dimensional weak field in the vicinity of said three-dimensional region and a three-dimensional strong field surrounding said three-dimensional weak field.

Other objects and a fuller understanding of this invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of apparatus embodying the invention;

FIG. 2 is a perspective view of two of the coils removed from the apparatus of FIG. 1 to better show the construction;

FIG. 3 is an enlarged section of line 3-3 of FIG. 2; and

FIG. 4 is a schematic diagram of a wiring connection for the coils.

DESCRIPTION OF THE PREFERRED EMBODIMENT The figures of the drawing show a preferred embodiment of the invention but this is only by way of illustration, it is not to be taken as limiting, the invention being limited only by the hereinafter appended claims.

The plasma compression apparatus 11 of the invention includes generally plasma-generating means 12, envelope means 13 to contain the plasma, and magnetic field means. The plasma-generating means in one form of the invention is a high-potential source 17 which may be either a continuous or a pulsed DC source having a negative terminal connected to a conductive sleeve 18 and a positive terminal connected to a central electrode 19. These two elements form a plasma gun by having the central electrode 19 axially disposed within the conductive sleeve 18 for an arc discharge therebetween to ionize a gaseous or fluid medium in the envelope [3. This envelope means 13 may include a sealed envelope which in the preferred embodiment may be of glass or any other insulator in generally spherical shape 20 plus a tubular-connecting envelope 21 (shown cutoff in FIG. 1) between the sphere 20 and the plasma gun 18-19. The gaseous medium may be air, for example, and a vacuum source 22 connected to the envelope means 13 reduces the absolute pressure to 1-20 microns. The ionized particles which form the plasma are generated in the plasma gun 18-19 and then are repelled by the magnetic field of the arc discharge away from the plasma gun through the connecting envelope 21 and into the spherical envelope 20. It is at this location that the plasma is desired to be compressed.

The magnetic field means 14 is provided by conductors or Winding means 25 to conduct current. In the embodiment of FIGS. 1 and 2 a plurality of coils are shown and each coil has at least one conductor. Referring to only a single conductor of one of these coils, such conductor has a first portion 26, a second portion 27 and a third portion 28. The second portion 27 is disposed between the first and third portions 26 and 28. Each of the conductors in each of the coils has such first, second and third portions. All of the first portions 26 are disposed in a first plane and all of the third portions 28 are disposed in a third plane substantially parallel to and spaced from the first plane. Additionally, the second portions 27 of the conductors are spaced apart from each other in a second plane disposed substantially parallel to and intermediate the first and third planes. The second portions 27 of the plural conductors are spaced further apart from each other in the second plane than the first portions 26 are spaced apart from each other in the first plane. Also, the second portions 27 of the conductors are spaced farther apart from each other in this second plane than the third portions 28 are spaced apart from each other in the third plane. A preferred configuration of the invention is that these second portions 27 are generally arcuate, and are arcs ofa circle so that when all of the second portions 27 are considered together they form a three-dimen' sional field means of conductors in a generally spherical shape. Generally, at the center of the sphere is a central region or three-dimensional region 30 which lies within the envelope means 13 because this envelope is concentrically disposed within this three-dimensional field means 14. Looking outwardly from this three-dimensional region 30, all of the second conductor portions 27 are concave as a means of forming this three-dimensional magnetic field means. Other configurations or shapes of the conductors are possible but this generally spherical shape is the preferred embodiment. As shown in FIG. 1, the first and third portions of the conductors, as they are formed into the individual coils, may be disposed as closely together as possible to better establish this threedimensional magnetic field means.

The cross section in FIG. 3 illustrates that each coil may be comprised of a number of closely wound conductors all carrying current in the same direction. Whereas six coils have been shown in FIG. I, it will be readily understood that the invention embraces the basic concept of two conductors, as shown in H6. 2, each having the first, second and third portions 26, 27, and 28. A greater number of coils such as four, six, eight or ten help to achieve a more nearly spherical three-dimensional field. FIG. 4 illustrates the six coils of the magnetic field means 14, and shows how these coils may be connected in series or as shown in FIG. 4 are connected in parallel to a DC source 29 for energization of the individual coils and for current flow through the conductor sources 26, 27 and 28.

The FIG. 2 shows the direction of current flow in the conductor portions 26, 27 and 28 as being upwardly directed, for example, being positive at the lower end and negative at the upper end of each conductor. This establishes a magnetic field for a first coil 31 which is clockwise as shown by the arrow 33. Also, for a second coil 32 the field of the conductor portion 27 is also clockwise s illustrated by an arrow 34. These two clockwise fields 33 and 34 are actually in opposition relative to the threedimensional region 30. This is true of all of the sets of coils of the magnetic field means 14. The combined effect of these magnetic fields is to produce a null field or weak field at the central three-dimensional region 30 surrounded by a strong field which is still within and bounded by the several second conductor portions 27. Because each of these second conductor portions 27 are as nearly semicircular as possible, the three-dimensional field is quite symmetrical and uniformly encircles this three-dimensional region 30 whereat a weak field is achieved.

A three dimensioned reference space is that which is bounded by the inner faces of the second conductor portions 27. Each of the plurality of coils 14 is disposed generally in a plane passing through the centrally disposed reference region 30.

With the plasma generated in and maintained in the envelope means 13 and in particular within the spherical envelope 20, the establishing of the magnetic field by the conductor portions 27 will compress the plasma in the threedimensional central region 30 because this is where the weakest field is encountered. All of the previously mentioned diffusions which have been described as deficiencies in the prior art structures combine to move the plasma toward this weaker field region. It has been discovered by observation that the ionized particles migrate toward the weaker field areas and the present invention takes advantage of this to cause this migration or movement to a weaker field area from which there is no escape. Consequently a high degree ofcompression of plasma is achieved.

The connecting envelope 21 has been shown as extending perpendicular to what could be considered the north and south poles of the sphere 20 and accordingly passes between two of the coils of the magnetic field means 14. An alternative construction would be to have the connecting envelope 2] turned degrees to extend along the polar axis and hence to pass out between the first conductor portions 26, for example. In either case, the magnetic field means establishing a threedimensional magnetic field which substantially completely surrounds the three-dimensional envelope 20. Also the threedimensional envelope 20 contains the plasma substantially all around the three-dimensional region 30.

The coils such as coils 3] and 32 contain at least one conductor fonning the second conductor portions 27 for each coil. There may be a plurality of conductor turns per coil as shown in FIG. 3. An alternative construction would be to have the generally spherical envelope 20 of a metallic conductor with a single first conductor portion 26 attached to the lower pole of this sphere and to have a third single conductor portion 28 connected to the upper pole portion of this sphere 20 with current flowing from the first conductor portion through the second conductor portion to the third conductor portion 28, the current flow on the second conductor portion 27 would then be substantially continuously over the surface of this hollow conductive sphere. This would still establish the substantially spherical magnetic field which would be weak at the central region 30 and strong surrounding this region 30. The return path for the current in such case may be in any desired matter such as a single conductor or a plurality of conductors such as shown by the outer portions of the six coils of the field means 14. Also in this case of a conductive sphere such sphere would be both the conductor portions 27 and it would also serve double duty as the envelope means.

This compression of the plasma has been observed in one physical apparatus embodying the principles of this invention, wherein the spherical envelope 20 was made of glass so that the plasma could be observed. In such physical embodiment, air was used as the gas and was ionized by a high-potential source of 10 kilovolts and was pulsed to produce pulses of plasma in the envelope means 13. A glow was observed which filled the entire envelope 20. Then when the coils of the magnetic field means 14 were energized this plasma was compressed to this three-dimensional region 30 as was evidenced by the flow being concentrated and accordingly appeared much brighter and was concentrated at this central threedimensional region.

One use for this plasma compression apparatus is to achieve controlled thermonuclear fusion. To accomplish this, either deuterium or a mixture of deuterium tritium would be used inside the envelope means 13. Some means would be used to ionize the gas within the envelope means and this plasmagenerating means could be the high-potential source 17 or it could be a radio frequency source to cause such ionization. Past attempts at compressing such fusionable plasma have achieved fusion for a maximum length of time of only a few milliseconds before the diffusion of the plasma terminated such fusion. The present apparatus by maintaining a constant and nearly spherical compression on the plasma will be much better able to obtain a controlled thermonuclear fusion.

Another application for this apparatus is in the combining of two substantially fluid substances. This may be in the metalrefining art, for example, wherein two different metals in either the liquid or gaseous state could be stirred together and mixed to form an alloy. In and near the three-dimensional region 30 the magnetic lines of force are circular and the ionized particles spiral around these lines of force and hence would achieve thorough mixing of one or more fluids within the envelope means 13. Accordingly, other fluids could be mixed such as an emulsion of immiscible liquids.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is 1. Plasma compression means for compressing a plasma toward a centrally disposed three-dimensional region,

said plasma compression means comprising, in combination,

means for generating a plasma,

three-dimensional envelope means surrounding said threedimensional region for containing said plasma substantially all around said three-dimensional region,

and three-dimensional magnetic field means having a threedimensional magnetic field substantially surrounding said three-dimensional envelope,

and said three-dimensional field having a three-dimensional weak field in the vicinity of said three-dimensional region and a three-dimensional strong field surrounding said three-dimensional weak field, said three-dimensional magnetic field means including a plurality of sets of opposed conductor means disposed around said threedimensional envelope means, each set of said opposed conductor means residing generally in a plane passing through said centrally disposed three-dimensional region and including at least first and second opposed concave portions looking outwardly from said three-dimensional region, and means to establish current flow through said first concave portion in a clockwise direction and through said second concave portion in a counterclockwise direction.

2. The structure of claim 1, wherein said three-dimensional field means is substantially spherical.

3. The structure of claim 1, wherein said concave portion is substantially arcuate.

4. A plasma compressor, comprising, in combination,

means for generating a plasma,

an envelope to contain the plasma,

a plurality of sets of first and second opposed conductor means surrounding said envelope,

each set of said first and second-opposed conductor means having first, second and third-spaced portions therealong with said second portions being intermediate said first and third portions,

said second spaced portions of said first and second-opposed conductor means being spaced further apart from each other than said first-spaced portions and spaced further apart from each other than said third spaced portions to encompass a three-dimensional reference space having a centrally disposed reference region,

each set of said first and second-opposed conductor means residing generally in a plane passing through said centrally disposed reference region, and means to establish current flow through said first conductor means in a direction opposite to that in said second conductor means to produce a magnetic field within said three-dimensional reference space with highest concentration of magnetic field on the surface of said three-dimensional reference space and with a minimum magnetic field in said centrally disposed reference region,

whereby said plasma is concentrated at said centrally disposed reference region.

5. A plasma compressor as set forth in claim 4, wherein said first and second opposed conductor means includes a plurality of coils disposed generally in planes passing through said centrally disposed reference region.

6. A plasma compressor as set forth in claim 4, wherein said second-spaced portions are concave looking outwardl from said centrally disposed reference region to establls said three-dimensional reference space.

7. A plasma compressor as set forth in claim 6 wherein said second-spaced portions are so disposed outwardly relative to each other as to cause said three-dimensional reference space to be substantially spheroidal.

8. A plasma compressor as set forth in claim 4, wherein said first spaced portions are adjacent each other and said thirdspaced portions are adjacent each other with said secondspaced portions disposed outwardly relative to each other to substantially enclose said three-dimensional reference space to concentrate said magnetic field therewithin.

9. A plasma compressor as set forth in claim 8, wherein said first and second opposed conductor means includes a voltage source to establish a weak field in said centrally disposed reference region and a strong field surrounding same. 

1. Plasma compression means for compressing a plasma toward a centrally disposed three-dimensional region, said plasma compression means comprising, in combination, means for generating a plasma, three-dimensional envelope means surrounding said threedimensional region for containing said plasma substantially all around said three-dimensional region, and three-dimensional magnetic field means having a threedimensional magnetic field substantially surrounding said three-dimensional envelope, and said three-dimensional field having a three-dimensional weak field in the vicinity of said three-dimensional region and a three-dimensional strong field surrounding said threedimensional weak field, said three-dimensional magnetic field means including a plurality of sets of opposed conductor means disposed around said three-dimensional envelope means, each set of said opposed conductor means residing generally in a plane passing through said centrally disposed three-dimensional region and including at least first and second opposed concave portions looking outwardly from said three-dimensional region, and means to establish current flow through said first concave portion in a clockwise direction and through said second concave portion in a counterclockwise direction.
 2. The structure of claim 1, wherein said three-dimensional field means is substantially spherical.
 3. The structure of claim 1, wherein said concave portion is substantially arcuate.
 4. A plasma compressor, comprising, in combination, means for generating a plasma, an envelope to contain the plasma, a plurality of sets of first and second opposed conductor means surrounding sAid envelope, each set of said first and second-opposed conductor means having first, second and third-spaced portions therealong with said second portions being intermediate said first and third portions, said second spaced portions of said first and second-opposed conductor means being spaced further apart from each other than said first-spaced portions and spaced further apart from each other than said third spaced portions to encompass a three-dimensional reference space having a centrally disposed reference region, each set of said first and second-opposed conductor means residing generally in a plane passing through said centrally disposed reference region, and means to establish current flow through said first conductor means in a direction opposite to that in said second conductor means to produce a magnetic field within said three-dimensional reference space with highest concentration of magnetic field on the surface of said three-dimensional reference space and with a minimum magnetic field in said centrally disposed reference region, whereby said plasma is concentrated at said centrally disposed reference region.
 5. A plasma compressor as set forth in claim 4, wherein said first and second opposed conductor means includes a plurality of coils disposed generally in planes passing through said centrally disposed reference region.
 6. A plasma compressor as set forth in claim 4, wherein said second-spaced portions are concave looking outwardly from said centrally disposed reference region to establish said three-dimensional reference space.
 7. A plasma compressor as set forth in claim 6 wherein said second-spaced portions are so disposed outwardly relative to each other as to cause said three-dimensional reference space to be substantially spheroidal.
 8. A plasma compressor as set forth in claim 4, wherein said first spaced portions are adjacent each other and said third-spaced portions are adjacent each other with said second-spaced portions disposed outwardly relative to each other to substantially enclose said three-dimensional reference space to concentrate said magnetic field therewithin.
 9. A plasma compressor as set forth in claim 8, wherein said first and second opposed conductor means includes a voltage source to establish a weak field in said centrally disposed reference region and a strong field surrounding same. 